In avenging a three-point defeat in Holland back on December 2, EWE Baskets improved to 3-2 while dropping MyGuide to 2-3.
Hapoel Jerusalem and Olympia are both 2-2 and are set to square off on Wednesday in this week's other Group E game.
German outfit EWE Baskets, playing in Europe this season for the first time, held a 56-54 lead with 6:50 left after a Teddy Gipson three-point play for the Dutch team.
EWE Baskets then put the result beyond doubt.
Cameroon national team center Ruben Boumtje Boumtje answered with a lay-up and Jasmin Perkovic, Je'Kel Foster and Rickey Paulding followed with three-pointers as the Germans opened up a 67-54 advantage.
The Amsterdam team never recovered, getting no closer than eight points the rest of the way.
Jason Gardner and Boumtje Boumtje each had 15 points for EWE Baskets.
Arie Shivek, coach of EclipseJet MyGuide:
"We started well and played according to our gameplan. think we did a decent job in holding Oldenburg to 34 first-half-points. We then missed some easy shots in the third quarter and Oldenburg hit some big three pointers. The game was lost in that period."
Peter van Paassen, player of EclipseJet MyGuide:
"Like coach Shivek said, we played a pretty good first half. Oldenburg started knocking down big shots in the third quarter and did a good job of controlling the game the rest of the way."
Jasmin Perkovic, player of Oldenburg:
"I'm happy with the win. I think we played better than we did in Amsterdam. I'm excited about the fact that we have the chance to make it to the next round. We now have seven days to prepare for the game against Jerusalem."
Predrag Krunic, coach of Oldenburg:
"I'm satisfied with the win. We played against a good team, which was well coached. I think we played solid basketball in three out of the four quarters. Once we started to rebound better, we gained control of the game. It would be a step in the right direction for this ball club if we made it into the next round."